1. Field of the Invention
The present invention relates to electronic paging systems and pagers. More particularly, the present invention relates to methods and apparatus for providing a secure message paging system.
2. Art Background
Radio paging systems are widely utilized in today's mobile environment. Typically, a person carries a small radio receiving device, i.e. "the pager". A central control system activates the pager by transmitting a radio signal recognizable by the pager. Upon receipt of the radio signal, the pager notifies the user of the page by producing an audible sound, vibrating, or displaying a message.
As the popularity of pagers has increased so has the sophistication and functionality of pagers. There are three kinds of pagers commonly in use today: tone pagers, numeric pagers, and alphanumeric pagers. Tone pagers simply beep or vibrate upon receiving a page signal. The recipient of a page from a tone pager must know who sent the message in order to respond to the page. Numeric pagers receive a signal consisting of a string of digits, 0 through 9, and display the digits on a small display on the pager. The recipient of a page on a numeric pager responds to the page by telephoning the number that appears on the display screen. Alphanumeric pagers provide the most information to the page recipient. Alphanumeric pagers receive signals which contain an encoded string of letters and digits and display the string on a small display screen on the pager.
A person wishing to contact someone via a paging device contacts the central control system and requests that a signal be sent to a specific pager. For example, a person may dial a telephone number for the central control system and using the telephone keypad, enter in an identification number for the pager to be contacted. Alternately, a different telephone number may be assigned to each pager such that the telephone number dialed to contact the central control system identifies the pager to be contacted. The telephone keypad can be further utilized to key in a numeric string to be sent to the pager. In more sophisticated alphanumeric-type pager systems, a terminal device such as a workstation may be utilized to contact the central control system through a computer network to identify the pager to be contacted and to supply a message to be sent. Once the request is received by the central control system, the message is sent to the pager via radio broadcast.
Typically, a pager message consists of two parts: a pager address and a message body. The pager address identifies the which particular pager unit a message is directed to. The message body contains the string of letters and numbers which are to be displayed on the display screen.
However, due to the nature of radio broadcast, the transmission of a message to a pager is not secure. That is, unauthorized access to pager messages can occur since pager messages can be easily intercepted by anybody monitoring the radio broadcast frequency. Furthermore, certain information may be obtained just by being able to identify the recipient of the pager message. A pager message can be intercepted and responded to without the intended recipient's authorization. These security problems cause breaches in privacy and accuracy of the message. The unauthorized interception and reading of pager messages is even more an issue with alpha-numeric pagers, as the information that the sender intended for the receiver is contained within the message sent to the pager.
However, many encryption systems require specialized or substantial hardware and/or software to implement. In order to provide an effective, secure paging system, the security should be provided without changing the infrastructure of the available paging systems.
In addition, it is preferred that a secure paging system be implemented which does not require the message originator to have any knowledge of the security features of the pager system and therefore is transparent to the originator.
Most alphanumeric pagers currently being sold have an internal clock that must be set by hand, and that can be used to show the current time. One problem with these pagers is that it is difficult to keep the internal clock set properly. This is particular true for travelers who must change the internal clock when they travel between time zones. It would be convenient if the internal clock in the pager could set itself automatically.